← All guides · Updated 2 November 2026
How to read your energy bill (and check it's right)
Energy bills can look confusing, but most of the cost comes from just two numbers: the unit rate and the standing charge. Once you know where to find them, you can check your bill and compare deals properly.
The two charges
- Unit rate: the price for each kilowatt hour (kWh) of gas or electricity you use, shown in pence per kWh.
- Standing charge: a fixed daily amount you pay to be connected, even if you use no energy. Ofgem says it covers costs such as keeping the network running and some government schemes.
Ofgem explains the basic calculation: your energy use in kWh times the unit rate, plus the daily standing charge times the number of days, plus VAT (currently 5% on household energy).
What else to check on your bill
- Your tariff name and type. Is it fixed, or a standard variable tariff (covered by the price cap)?
- Tariff end date and exit fees, if you're on a fixed deal.
- Meter readings. Look for "E" (estimated) or "A"/"C" (actual or customer reading). Estimated readings can be too high or low. Submit your own reading if needed.
- Your annual usage in kWh. You need this to compare deals fairly.
- Your balance. Are you in credit or debit? If you're in credit, you can usually ask for it back.
The price cap
If you're on a standard variable tariff, the Ofgem price cap limits the unit rate and standing charge your supplier can charge. It doesn't cap your total bill: if you use more, you pay more. Ofgem publishes the current cap levels by region and payment method; check Ofgem: price cap unit rates and standing charges for the latest figures.
Fixed deals and the 49-day window
On a fixed tariff, your unit rate and standing charge are fixed until the end date. Ofgem says you can switch without paying exit fees in the last 49 days of a fixed deal. Your supplier should contact you before it ends. If you do nothing, you'll usually move to a variable tariff.
Is a fixed deal worth it?
It depends on the price compared to the cap and on what you expect prices to do. Citizens Advice suggests comparing the total cost based on your own usage, not just the unit rate, because a low unit rate with a high standing charge may cost more if you use little energy.
A simple check
Take one bill and multiply the kWh used by the unit rate, add the standing charge times the number of days, then add VAT. If your answer is very different from the bill total, check the meter readings and whether there are any other charges or credits, and ask your supplier to explain.
If you can't pay
Contact your supplier as early as you can. Suppliers must work with you on a payment plan you can afford. Citizens Advice can help too.
Check your own bill
Upload your energy bill or enter your tariff end date and monthly cost. Bill Fighter shows when your 49-day switching window opens and what a cheaper deal would save.
Free, no sign-up. Uploaded bills are read and deleted straight away.
Related guides
- Council tax single person discount: how to get 25% off
- Broadband social tariffs: who qualifies and how to switch
Sources
- Ofgem: how your bill is calculated
- Ofgem: price cap unit rates and standing charges
- Ofgem: switch your energy supplier
- Citizens Advice: choosing an energy tariff
Last checked 02/11/2026. Rules change, so check the linked pages before you act. This is general information, not financial or legal advice.